1. Field of the Invention
This invention relates generally to composite structural wood substitutes, and more particularly to a concrete/bamboo composite structure formed of stranded bamboo segments stripped of all epidermis material and formed into layers surrounding a cured concrete core bonded together under high pressure and temperature into a composite concrete and solid bamboo structural product.
2. Description of Related Art
Because we have, as a world community, substantially depleted the original tree growth in our forests with which we were blessed, manufacturers of wood products utilized in the construction industry have had to resort to next-generation tree growth which, in many cases, produces substantially less wood product as they are necessarily cut down well short of full maturity in size.
Composite lumber formed of wood products such as oriented strand board (OSB) as is described in the SBA Structural Board Association U.S. Edition 2005 Manual, has become a popular substitute for solid wood products. By utilizing substantially all of the wood growth of next-generation forests as facilitated by the OSB process, a very substantial composite wood-based product rivaling the strength of solid wood beams is achievable.
Because of its strength and rapid re-growth cycle, another alternative is to turn to bamboo composite products utilized to form composite wood replacement or alternative beam, plywood and structural products. One particularly interesting bamboo wood replacement product is disclosed in Plaehn, in U.S. Pat. No. 5,543,197. This disclosure teaches a composite bamboo beam which includes segments of bamboo stalk, either split or whole, which are longitudinally aligned and randomly stacked and then compressed and bonded together to form a cohesive bamboo composite structure from which beams of a desired dimension may be cut. Strength consistency is lacking in this bamboo product, however.
Fujii, et al. has been issued U.S. Pat. Nos. 5,741,589 and 6,010,585. These patents are directed to construction materials made of a woody group material consisting of finely split pieces of wood, bamboo or the like and cement. U.S. Pat. No. 7,276,551 to Pageau discloses a cement composition including wood fibers and wood shavings.
U.S. Pat. No. 5,573,348 to Morgan discloses structural members formed of cement-based slurry infiltrated fiber composite material, FIG. 6 of which is referred to as a railroad tie. Leon teaches structural members fabricated of wood products and thermoplastics products in U.S. Pat. No. 7,172,136. Thomas, et al. teaches a cementitious composite of cellulosic debris and Portland cement in U.S. Pat. No. 5,196,061.
A process for making a cement mixture containing fibers is disclosed in U.S. Pat. No. 5,167,710 to Leroux, et al. and a method for constructing buildings using fiber-reinforced cellular concrete products is taught in U.S. Pat. No. 6,976,345 to Keshmiri. Hayakawa, et al. teaches a cement composition having pulp fiber in U.S. Pat. No. 5,047,086.
Friberg discloses cementuous fiber impregnated construction compositions and a process therefor in U.S. Pat. No. 4,799,961 and Sattler, et al. teaches construction materials in which fibers of ligno-celluloses and Portland cement are utilized. Bayasi teaches recycled fiber reinforced, moldable cementitious compositions in U.S. Pat. No. 5,733,671.
U.S. Pat. No. 4,985,119 to Vinson, et al. teaches cellulose fiber-reinforced construction materials for building and construction and Creamer, et al. discloses fiber reinforced aerated concrete compositions in U.S. Pat. No. 6,773,500. Finally, Merkley, et al. teaches fiber cement composite materials and discloses fiber treatment, formulation, method and final construction product in U.S. Pat. No. 6,872,246.
A previous invention also utilizes bamboo segments in a unique way to develop an even stronger bamboo beam structure for use in the building industry. The process of compressing and final beam formation is taught by Trautner in U.S. Pat. No. 3,723,230, the teaching of which is incorporated herein by reference. Trautner teaches a continuous press for pressing glue-coated consolidatable press charges into structural composite wood structural components.
A significant aspect of the previous invention, as with this continuing disclosure, is the recognition that bamboo segments may only be securely glued into a cohesive bamboo composite structure after the outer epidermis surface material and nodes have been machined, abraded or otherwise stripped therefrom. Current glue technology is somewhat inadequate in its binding effect with a bamboo surface which still retains any portion of the epidermis husk or inner membrane material prior to the drying and bonding of the bamboo segments as will be more described more completely herebelow.